Right off the top, one of the greatest differences between Biblical meditation and transcendental or yoga meditation is that instead of emptying one's mind to quietness, it is about continually filling one's mind with God's word. There certainly are levels of peace, wisdom, motivation, and balance that we may attain naturally through our own practices of mental stillness, but what the Scriptures refer to in the 30+ times that they speak of "meditation", "pondering", etc. is much greater and leads to having access to even more.
"This book of the law shall not depart out of thy mouth; but thou shalt meditate therein day and night, that thou mayest observe to do according to all that is written therein: for then thou shalt make thy way prosperous, and then thou shalt have good success." - Joshua 1:8